1. Field of the Invention
The present invention relates to an image forming apparatus having a latent image carrier, a first of developing unit having a plurality of developing units and provided so as to face the latent image carrier at a predetermined developing position, and a second developing unit provided so as to face the latent image carrier at a developing position different from that for the first developing unit.
2. Related Background Art
In an image forming apparatus provided with a rotative color developing unit and a separate black developing unit, if the rotative color developing unit fails rotate correctly, this is treated as an error in the entire apparatus. Consequently, subsequent image formation is impossible. However, if a user forms black and white images more frequently than color images, it is desirable that even if only the rotative color developing unit rotates incorrectly, this is not treated as an error in the entire apparatus, so that the image forming apparatus allows at least only black and white images to be formed.
It is thus an object of the present invention to provide an image forming apparatus wherein even if the rotative color developing unit rotates incorrectly, only color image formation is disabled, while black and white images are allowed to be formed, depending on the positions of developing units of the rotative color developing unit, thereby minimizing the downtime of the apparatus to make the apparatus more convenient for the user.
The present invention provides an image forming apparatus including a latent image carrier, a first developing unit having a plurality of developing units and provided so as to face the latent image carrier at a predetermined developing position, and a second developing unit provided so as to face the latent image carrier at a developing position different from that for the first developing unit, and having a first mode in which images are formed using the first developing unit and a second mode in which images are formed without using the first developing unit, wherein such control is provided that the first mode is avoided depending on an operational status of the first developing unit. This minimizes the downtime of the apparatus to make the apparatus more convenient for the user.
Furthermore, such control is provided that if it is detected that the first developing unit is rotating incorrectly, the first mode is avoided and images are formed in the second mode, depending on the rotative position of the first developing unit. This minimizes the downtime of the apparatus to make the apparatus more convenient for the user.
If it is detected that the first developing unit is rotating incorrectly, the second developing unit is used to form images if this is possible, on the basis of the rotative position of the first developing unit. This minimizes the downtime of the apparatus to make the apparatus more convenient for the user.
According to the present invention, in an image forming apparatus such as a copier which is provided with a rotative color developing unit and a separate black developing unit, if the rotative color developing unit does not rotate correctly but black and white images can be formed, then only color image formation is disabled, while black and white images are allowed to be formed. This minimizes the downtime of the apparatus to make the apparatus more convenient for the user.
Furthermore, according to the present invention, if it is detected that the first developing unit is incorrect during the use of the first developing unit, when it is possible to form the images by using the second developing unit, such an effect as to improve the convenient of the user can be realized by using the second developing unit in accordance with the user""s intention to continue the image formation.
An embodiment of the present invention provides an image forming apparatus (an image forming apparatus 100, shown in FIG. 1) including a latent image carrier (a photosensitive drum 111, shown in FIG. 1), a first developing unit (rotative color developing means 116, shown in FIG. 1) having a plurality of developing units (developing units 122, 123, and 124 corresponding to magenta, yellow, and cyan, respectively, as shown in FIG. 1), and a second developing unit (a black developing unit 115, shown in FIG. 1) provided so as to face the latent image carrier at a developing position different from that for the first developing unit. The apparatus further includes an operation determining unit (a program stored in a ROM in a main body control unit 200) that determines an operational status of the first developing unit, a first mode (a color image formation mode) in which the first developing unit is used to form an image, and a second mode (a B/W image formation mode) in which an image is formed without using the first developing unit, such control being provided that the first mode is avoided (the main body control unit 200 disables the color image formation mode, while enabling the B/W image formation mode) on the basis of a result of the determination by the operation determining unit. Other objects and features of the present invention will be apparent from the following specification and drawings.